Ursane-type triterpenoids, steroids and phenolics from the stem bark and leaves of Nauclea orientalis (L.) L. (Rubiaceae)

Phytochemical investigation of the stem bark and leaf extract of Nauclea orientalis led to the isolation and identification of the three ursane-type triterpenoids rotundic acid, (3β)-3,19,23,24-tetrahydroxyurs-12-en-28-oic acid, 3-oxo-19,23,24-trihydroxyurs-12-en-28-oic acid, the two steroids β-sitosterol, β-sitostenone, the two megastigmane derivatives blumenol A and blumenol A glucoside, the isocoumarine trans-4-hydroxymellein, as well as the flavonole glycoside rutin. From the crude stem bark extract, we performed an anti-bacterial assay against four Gram positive and six Gram negative bacterial strains. An acetylcholinesterase inhibitory assay was performed from the crude extracts and rotundic acid, (3ß)-3,19,23,24-tetrahydroxyurs-12-en-28-oic acid and β-sitostenone. Both assays showed only weak effects. Contact toxicity determined via topical application revealed increased mortality of Spodoptera exigua caterpillars. The chemophenetic significance of ursane-type triterpenoids for the genus Nauclea is discussed briefly. [Display omitted] •Three ursane-type triterpenoids and six other compounds could be isolated from Nauclea orientalis.•3-oxo-19α,23,24-trihydroxyurs-12-en-28-oic acid (3) was isolated the first time from a Rubiaceae species.•The lipophilic stem bark extract showed contact toxicity on Spodoptera exigua larvae.